2-nitrophenyl dialkyl phosphates and thiophosphates



Patented Aug. 29, 1950 UNITED STATES PATENT OFFICE 2-NITBOPHENYL PHOSPHATES AND THIOPHOSPHATES John H. Fletcher, Riverside, Conn., assignor to 7 American Gyanamid Company, New York, N. Y.,

a corporation of Maine No Drawing. Application December 31, 1947, Serial No. 795,115

10 Claims.

in which R1 and R2 are chosen from the group consisting of alkyl, aralkyl, and aryl radicals, X is a member of the group consisting of sulfur and oxygen, Z is a member of the group consisting of halogen and alkyl radicals, and m represents an integer not greater than 2.

In the new compounds R1 and R2 may be the same or diflerent radicals. Furthermore, it is to be understood that when the Rs stand for alkyl radicals, they represent both the straight chain and branch chain, the saturated and unsaturated, and the eycloaliphatic hydrocarbon radicals. The R1 and R2 radicals may also carry halogen substituents, particularly chlorine and bromine. Typical examples of these radicals are methyl, ethyl, n-propyl, isopropyl, isobutyl, sec.-amyl, n-hexyl, Z-ethylhexyl, n-octyl, n-decyl, n-dodecyl, oleyl, cetyl, ceryl, allyl, bromomethyl, 2-chloroethyl, cyclohexyl, benzyl, phenyl, and i-chlorophenyl.

The compounds of this invention possess general pest-control characteristics, including insecticidal, rodenticidal, and fungicidal properties. Many of the members possess desirable flotation properties and have the characteristics of high pressure lubricants when used as oil additives. These compounds may also be employed as corrosion inhibitors.

These organic phosphate esters may be readily prepared by reacting a chlorophosphate of the general formula in which R1, R2, and K have the meaning shown above, with an alkali-forming metal phenoxlde of the general formula 2 in which Z and m have the meaning shown above, and Y represents an alkali-forming metal, in the presence of an inert organic solvent.

The term alkali-forming metal as used in this specification and in the appended claims is intended to cover the alkali metals (including ammonium) and the alkaline earth metals.

The chlorophosphate compounds employed in the present process as shown above, namely the organic chlorophosphates and chlorothiophosphates, may be prepared according to the methods described in the Journal of the American Chemical Society, volume 67, No. 10, page 1663.

A typical reaction in which diethyl chlorophosphate is reacted with sodium 4-chloro-2-nitrophenoxlde to produce 4-chloro-2-nitrophenyl diethyl phosphate may be illustrated as follows:

High yields of the desired products are obtained by carrying out the reaction in the presence of an inert organic solvent, the latter serving particularly as a solvent for the solid alkali-forming metal phenoxide. Suitable inert solvents include the ketones such as, for example, acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl benzyl ketone, cyclohexanone, acetophenone, and the like; aliphatic esters such as ethyl acetate, amyl acetate, 2-ethy'1hexyl acetate, methyl propionate, methyl butyrate, ethyl butyrate, and isopropyl butyrate; saturated aliphatic nitriles such as acetonitrile and propionitrile; dioxane, nitrobenzene, 1,2-dimethoxyethane, and the trialkyl phosphates such as trimethyl phosphate, triethyl phosphate, and triisopropyl phosphate.

Organic liquids which are poor solvents for the alkali-forming metal phenoxides, and hence are less suitable in the present process, include chloroibenzene, toluene, xylene, diethyl ether, chloroform, carbon disulflde, and carbon tetrachloride. Water and the alcohols in general may be used as solvents for the alkali-forming metal phenoxides. However, they are less satisfactory in the pro ss inasmuch as they tend to react with the chlorothiophosphate and chlorophosphate compounds,

The reaction is preferably carried out at a temperaturewithin the range of from about 30 to 150 C. However, temperatures outside of this range may be employed depending upon the type of reactants and solvents utilized.

An alternative method of preparing the compounds of the present invention consists in employing in lieu of the alkali-forming metal phenoxide the corresponding phenol and a basic alkali-forming metal compound, the latter having suiiicient alkalinity to neutralize the phenol. Obviously, this procedure avoids the initial preparation and isolation of the alkali-forming metal phenoxide. Such basic alkali-forming metal compounds include sodium carbonate, potassium carbonate, barium carbonate, magnesium carbonate, lithium carbonate, sodium hydroxide, potassium hydroxide, calcium hydroxide, strontium hydroxide, magnesium hydroxide, sodium borate, tripotassium arsenate, tripotassium arsenite, sodium pyrophosphate, magnesium pyrophosphate, potassium pyrophosphate, barium phosphate, trisodium phosphate, and the like.

Employing the above procedure in the preparation of di-n-butyl 2-nitro-4-tolyl thiophosphate, the reaction may be illustrated as follows:

The following examples will further illustrate the invention.

Example 1 34.7 grams (0.2 mol) of 4-chloro-2-nitrophenol, 21.2 grams (0.2 mol) of anhydrous sodium carbonate, and 200 cc. of methyl ethyl ketone were mixed together at room temperature with good stirring in a vessel equipped with a reflux condenser. 37.7 grams (0.2 mol) of diethyl chlorothiophosphate were added, and the mixture was stirred and heated at reflux for three hours. After cooling to room temperature, the mixture was filtered to remove the sodium chloride and sodium bicarbonate, and the filtrate heated under reduced pressure to distill off the methyl ethyl ketone. The residual brown oil was dissolved in 200 cc. of toluene, washed with 5% sodium carbonate solution, and then with sodium chloride solution. The toluene extract was dried over Drierite, filtered, and the toluene removed by distillation at reduced pressure. A small amount of unreacted diethyl chlorothiophosphate was also removed by distillation in vacuo. The residual product, 4-chloro-2-nitrophenyl diethyl thiophosphate, weighing 53.5 grams, was a clear light brown liquid having a refractive index n 1.5402.

Example 2 The procedure of Example 1 was employed using 34.7 grams of 4-chloro-2-nitrophenol, 21.2 grams of anhydrous sodium carbonate, 100 cc. of methyl ethyl ketone, and 34.5 grams 0i diethyl Example 3 A mixture consisting of 0.2 mol of 2-nitro-D- cresol and 0.2 mol of anhydrous sodium carbonate was heated in cc. of methyl ethyl ketone until the orange-red sodium salt of 2-nitrop-cresol was formed. 0.2 mol of diethyl chlorothiophosphate was then added, and the reaction mixture refluxed for four and one-half hours. The resulting mixture was cooled to room temperature, filtered, and the filter cake washed with methyl ethyl ketone. The combined .flltrate and washings were heated under reduced pressure to remove the ketone and any unreacted diethyl chlorothiophosphate. The residue was taken up in 77 cc. of benzene, washed twice with dilute sodium hydroxide solution, once with water, and then dried over Drierite. Upon distillation, 39 grams of diethyl 2-nitro-4-tolyl thiophosphate were obtained, boiling at 175-185 C./0.5-1.0 mm.,

'and having a refractive index a 1.5283.

Example 4 0.12 mol of 2,4-dichloro-6-nitrophenol was heated with concentrated aqueous alkali (containing 5 grams of sodium hydroxide) in 225 cc. of xylene until all the water had distilled azeotropically. 0.12 mol of diethyl chlorothiophosphate in cc. of methyl ethyl ketone was added to the cooled xylene slurry, followed by refluxing the resulting mixture for a period of twelve hours. The reaction mixture was filtered and the filtrate concentrated in vacuo. The residue Was taken up in benzene, washed with dilute sodium hydroxide solution, and then with water, and dried over Drierite. The solution was heated under reduced pressure to remove the benzene and any unreacted diethyl chlorothiophosphate. The residual product, 2,4-dichloro-6-nitrophenyl diethyl thiophosphate, was a dark brown oily liquid.

The phosphate esters of this invention may be employed in controlling many types of insects and mites such as, for example, the black bean aphid, green peach aphid, pea aphid, chrysanthemum aphid, greenhouse thrips, California red scale, citrus red spider, greenhouse red spider, milkweed bug, mealy bug, sow bug, German cockroach, Southern army worm, yellow fever mosquito, malarial mosquito, Mexican bean beetle, confused flour beetle, and black carpet beetle.

These new compounds may also be used in combination with insecticides such as lead arsenate, nicotine, rotenone, pyrethrum, benzene hexachloride, a,a-di(p-chlorophenyl) -B, B,B-trichloroethane, dodecyl thiocyanate, phenothiazine, and the like; with fungicides such as sulfur, various copper compounds, mercury salts, and the like; and

with various types of plant foods and fertilizers. Additives of high alkalinity are to be avoided, since the organic phosphates are unstable in vehicles' having a pH in water greater than about While the invention has been described with particular reference to specific embodiments, it is to be understood that it is not to be limited thereto, but is to be construed broadly and restricted solely by the scope of the appended claims.

I claim: 1. Phosphate esters of the general formula in which R1 and R2 are chosen from the group consisting of alkyl, aralkyl, and aryl radicals, X is a member of the group consisting of sulfur and oxygen, Z is a member of the group consisting of halogen and alkyl radicals, and m represents an integer not greater than 2, which includes the step of reacting a ohlorophosphate compound of the general formula in which R1 and R2 are chosen from the group consisting of alkyl, aralkyl, and aryl radicals, and X is a member of the group consisting of sulfur and oxygen, with an alkali-forming metal phenoxide of the general formula in which Z is a member of the group consisting of halogen and alkyl radicals, m represents an integer not greater than 2, and Y represents an alkali-forming metal, in the presence of an inert organic solvent. I

6. The method of claim 5 in which the reaction is carried out at a temperature within the range of from about 30 to 150 C.

7. A method of preparing a phosphate ester of the general formula NO: (z),-

in which R1 and R2 are chosen from the group consisting of alkyl, aralkyl, and aryl radicals, X is a member of the group consisting of sulfur and oxygen, Z is a member of the group consisting of halogen and alkyl radicals, and m represents an integer not greater than 2, which includes the step of reacting together a chlorophosphate compound of the genera/l formula in which R1 and R2 are chosen from the group consisting of alkyl, aralkyl, and aryl radicals, and X is a member of the group consisting of sulfur and oxygen, a phenol of the general formula HOG in which Z is a member of the group consisting of halogen and alkyl radicals, and 122 represents an integer not greater than 2, and a basic alkaliforming metal compound having suiicient alkalinity to neutralize the phenol, in the presence of an inert organic solvent in which the inert organic solvent is a, ketone.

8. A method of preparing 4-chloro-2-nitrophenyl diethyl thiophosphate which includes the step of reacting together 4-chloro-2-nitropheno1, sodium carbonate, and diethyl chlorothiophosphate in the presence of methyl ethyl ketone.

9. A method of preparing diethyl Z-nitro-- tolyl thiophosphate which includes the step of reacting together Z-nitro-p-cresol, sodium carbonate, and diethyl chlorothiophosphate in the presence of methyl ethyl ketone.

10. A method of preparing 4-chloro-2-nitrophenyl diethyl phosphate which includes the step of reacting together 4-chloro-2-nitrophenol, sodium carbonate, and diethyl chlorophosphate in the presence of methyl ethyl ketone.

' JOHN H. FLETCHER.

REFERENCES CITED The following references are of record in the file of this patent:

' UNITED STATES PATENTS Name Date Clemmensen Dec. 4, 1934 OTHER REFERENCES Number Developments in Methods and Materials for Control of Plant Pests and Diseases in Germany," by H. Martin et al., dated May-June 194:6,page 22. 

1. PHOSPHATE ESTERS OF THE GENERAL FORMULA 